Recently, receiver apparatuses capable of receiving wireless signals transmitted from satellites have been installed in moving bodies such as vehicles, mobile telephones, and the like. By using GPS (Global Positioning System) positioning, it is possible to estimate the position of the moving body in which the receiver apparatus is installed. Such position estimating technology that uses a receiver apparatus is an important base technology in a wide range of fields such as navigation, security and entertainment. However, position estimating technology based on GPS positioning requires a long time at startup for supplementary synchronization and is difficult to use inside buildings and underground that are out of range for the wireless signals from satellites.
Also, as disclosed in Japanese Laid-Open Patent Publication No. 2008-104029 for example, a method of estimating the position of a wireless terminal based on the signal strength at the wireless terminal of wireless signals transmitted from base stations on a wireless LAN (Local Area Network) has been proposed. More specifically, it is possible to estimate the position of the wireless terminal based on position information of respective base stations registered in advance and the distances between the base stations and the wireless terminal calculated from the respective signal strengths of the wireless signals. Since base stations on a wireless LAN are also set up inside buildings and underground, by using this method of estimating, it is possible to carry out position estimation inside buildings and underground which has been difficult for position estimating technology based on GPS positioning.